LARGE WILDLIFE LOSS ALTERS TICK ABUNDANCE AND SURVIVORSHIP IN A CALIFORNIA RANGELAND
Devyn A Orr; University of California Santa Barbara; UC Santa Barbara, Noble Hall 2125, Santa Barbara, CA, 93106; (510) 847-7657; devyn@ucsb.edu; Emma Duge, Carina Motta, Hillary Young
Populations of large wildlife are declining around the world, with cascading effects on ecosystem structure and function. One such function critical to the health of both humans and wildlife is control of tickborne disease. Directly, large wildlife can serve as hosts for ticks, maintaining disease transmission cycles. However indirectly, they can modify habitat and suppress abundance of intermediate hosts and ticks, thereby decreasing disease risk. While numerous studies have attempted to correlatively link wildlife loss to changes in disease, few manipulative studies exist, and these have been done at small spatial scales unable to adequately capture indirect pathways. Using a large-scale replicated exclosure experiment at Tejon Ranch, Kern Co., CA, we show how removal of large wildlife led to 1) increases in total cover and biomass of understory vegetation, 2) increases in survivorship rates of juvenile ticks, 3) modest changes in intermediate host densities (rodents), and 4) an increase in the density of questing ticks. Notably, these responses were strongest at drier sites, and sites accessible to both wildlife and livestock had the lowest tick densities. Our results suggest that particularly in arid systems, maintaining high densities of wildlife and/or livestock may be an effective tool for tickborne disease control.
The Anthropocene: Pathogens & Invasive Species   Student Paper